Printed circuit boards are commonly found in many electronic devices, including, for example, the internal circuitry for controlling and operating an appliance. Printed circuit boards can mechanically support and electrically connect electronic components. For example, printed circuit boards can include vias through which pins the electronic components are inserted. The pins can then be soldered to the rear surface of the printed circuit board to secure the electronic components in place.
Printed circuit boards and their associated components and circuitry can be susceptible to damage or fire due to localized overheating. For example, fault conditions such as high resistance connections, component failures, arc tracking, ground faults, or other fault conditions can result in localized overheating that can cause operational damage to the device or can generate a fire. In particular, if the fire spreads to other portions of the device, then flames may spread beyond the product as well.
One attempted solution to the problems discussed above is to enclose the printed circuit board within an enclosure that prevents the spread of fire. However, this solution requires additional structural components and undesirably complicates the design and positioning of components within the device. Furthermore, use of an enclosure does not prevent significant damage to the components within the enclosure. Therefore, use of an enclosure is generally directed only towards prevention of catastrophic fires, and does not intervene to minimize damage to the overheating components themselves.
Another attempted solution to the problems discussed above is the use of a thermal cut-off device which includes sensors to detect elevated temperatures in the area of the printed circuit board. However, the inclusion of temperature sensors and associated processing circuitry undesirably increases the cost and complexity of a device that may include many printed circuit boards.
Therefore, printed circuit board assemblies providing fault detection are desirable. In particular, printed circuit board assemblies that provide fault detection in a simple, low-cost, and localized fashion are desirable.